The present invention relates to a multiplex data transmitting equipment for sending transmission data and playback management information for utilizing it by using communication media, and a multiplex data receiving equipment for receiving reception data and playback management information for utilizing it by using the communication media.
A method called MPEG (Moving Picture Experts Group) is known as one of the methods of compressing digital video signals and digital audio signals. The MPEG system includes MPEG1 dealing with accumulation media with low bit rate, and MPEG2 realizing high picture quality of broadcast level and applicable to different screen sizes. In MPEG 2, the quantity of data processed per unit time is variable depending on the program or contents in order to vary the compression rate according to the screen size or required picture quality.
Moreover, as the standard of media using MPEG2, DVD (Digital Video Disc) standard is known. Concerning the information of digital video data or audio data compressed by MPEG2 system being readout from a disc conforming to the DVD standard, it is being requested to deliver the information to an external device by using a transmission channel, or feed it into other device from a device conforming to the MPEG2 or DVD standard.
Besides, in wireless and wired media, various methods have been proposed as means for transmitting digital video data and audio data conforming to MPEG2 or DVD standard.
As one of the means for transmitting such digital video data and audio data, for example, a system called IEEE 1394 High Performance Serial Bus (hereinafter called IEEE1394) is known. The IEEE1394 is the serial bus type communication media comprising both isochronous transmission mode capable of transferring real-time data necessary for transmission of video data and audio data, and asynchronous transmission mode.
The IEEE1394 operates on the basis of the period of every 125 microseconds (hereinafter called the cycle), and includes two transmission modes, that is, the isochronous transmission mode for transmitting data in one or a plurality of bands in the fore portion of each cycle, and the asynchronous transmission mode for transmitting data in the remaining time after isochronous transmission.
If real-time data transfer is necessary, as in the case of digital video data or audio data, the data is transferred by this isochronous transmission, and if real-time data transfer is not necessary, in case of such as some data or control information, they are transferred by the asynchronous transmission.
In the case of isochronous transmission, prior to the transmission, the time duration used in one cycle (that is, the bandwidth for transmitting data) must be acquired from the device (node) for controlling the band management. In the IEEE1394, there is one node for managing the band used in isochronous transmission on the bus, and a device (node) for using the band width must acquire the band width to be used from this band management node. The device (node) acquiring the band width can monopolize the transmission to the acquired band width.
Thus, the node for isochronous transmission can transmit the data in the band acquired in the communication media. The data transmitted by isochronous transmission is sent out as a packet (a serial data bit stream synchronized with the clock) determined in the IEEE1394. In isochronous transmission, real-time data can be transferred by transferring the quantity of data predetermined in each cycle.
However, in the disc conforming to the DVD standard, information conforming to MPEG2 such as digital video data and audio data, and procedure information and selection information for playing back the digital video data and audio data are recorded in mixture. In the information group having such a signal format, by using the procedure information and the selection information for playing back the digital video data and audio data, the digital video data and audio data are reordered and then demodulated to obtain the original video signal and audio signal. On the other hand, when transmitting or receiving the signal before such demodulation process in the case of IEEE1394 isochronous transmission or the like, the transmitting method and receiving method of the procedure information and the selection information for playing back the digital video data or audio data have not been established yet.
Therefore, in the case of transfer of mixed data of information such as digital video data and audio data, and the procedure information and the selection information for playing back the digital video data and audio data according to the IEEE1394, as in DVD, when the digital video data and audio data being read out from the information source such as DVD are transmitted or received directly through a transmission channel, they are demodulated in the sequence of transmission or reception from the transmission channel, and the original picture or sound information may not be played back, or the function such as a change of playback procedure or selection of playback information cannot be realized at the reception side, and it is being demanded to solve such problems.
The present invention is intended to solve the above problems, and it is an object thereof to present a multiplex data transmitting equipment capable of transmitting procedure information and selection information for playing back digital video data and audio data, together with digital video and audio data, and a multiplex data receiving equipment capable of receiving such data, in transmission and reception of mixed data comprising information of pictures and sounds such as data recorded in recording media such as DVD and management information used in playing back.
To achieve the object, in the multiplex data transmitting equipment of the invention, a second packet stream obtained by inserting a packet of playback management information generated from the playback management information consisting of procedure information and selection information for playing back the digital video data and audio data into a first packet stream generated from transmission data such as digital video data and audio data, with a predetermined rate, or a rate designated from the device for receiving the data, is transmitted in one band of communication media, so that the function of reproducing the original information of picture and sound, changing the playback procedure, or selecting the playback information can be realized at the reception side.
According to the multiplex data receiving equipment of the invention, when a packet stream inserting playback management information such as the procedure information and the selection information for playing back the data at a predetermined rate into data such as digital video data and audio data is transmitted in one band of the communication media, the data such as digital video data and audio data, and the playback management information for playing back the data are separated from the received packet stream, and by generating playback data of the original digital video data and audio data by using these signals, the information of the original picture and sound can be reproduced, and the function such as the change of playback procedure and the selection of playback information can be realized at the reception side.
The invention further presents, for the ease of reception and playback processing at the reception side, a multiplex data transmitting equipment having functions for adding an identifier and attribute information to the packet and blocks for composing the packet, transmitting the packet of playback management information prior to the packet of video and audio data, and transmitting the packet of playback management information in other band than the band for transmitting the packet of video and audio data, and a corresponding multiplex data receiving equipment. Moreover, to process according to various requests at the reception side, it also presents a multiplex data transmitting equipment capable of demanding a start or stop of transmission of the playback management information to the transmission side from the reception side, and a corresponding multiplex data receiving equipment.